The description relates to network address translation for tunnel mobility.
A number of communication protocols, e.g., Mobile Internet Protocol (MIP) and IKEv2 Mobility and Multihoming Protocol (MOBIKE), allow access terminals (e.g., laptops and mobile phones) to roam among sub-networks at various locations while maintaining network connectivity. For example, in a system that complies with Mobile IP, an access terminal can have two addresses, a permanent home address and a care-of address, associated with the network the access terminal is visiting. A communication node that wants to communicate with the access terminal uses the home address of the access terminal as the destination address. The packets are routed through a home agent, which tunnels the packets to the access terminal's care-of address. When the access terminal wants to communicate with a communication node, the access terminal sends the packets to the communicating node through the home agent. For example, in a system that complies with the MOBIKE protocol, an access terminal can establish a security association with a security gateway, and can update its IP address using an informational request when the access terminal moves to a different access point.